Next: Using Texinfo Mode

Texinfo^[1] is a documentation system that uses a single source file to produce both on-line information and printed output. This means that instead of writing two different documents, one for the on-line help or other on-line information and the other for a typeset manual or other printed work, you need write only one document. When the work is revised, you need revise only one document. (You can read the on-line information, known as an Info file, with an Info documentation-reading program.)

• Create a conventional printed book or an Info file.
• What is an Info file?
• Characteristics of a printed book or manual.
• @-commands are used for formatting.
• General rules for writing a Texinfo file.
• How to write comments and mark regions that the formatting commands will ignore.
• What a Texinfo file must have.
• Usually, a Texinfo file has six parts.
• A short sample Texinfo file.
• Acknowledgements

Using Texinfo

A Texinfo file is a plain ascii file containing text and @-commands (words preceded by an `@') that tell the typesetting and formatting programs what to do. You may edit a Texinfo file with any text editor; but it is especially convenient to use GNU Emacs since that editor has a special mode, called Texinfo mode, that provides various Texinfo-related features. (See Texinfo Mode.)

Before writing a Texinfo source file, you should become familiar with the Info documentation reading program and learn about nodes, menus, cross references, and the rest. ( info, for more information.)

You can use Texinfo to create both on-line help and printed manuals; moreover, Texinfo is freely redistributable. For these reasons, Texinfo is the format in which documentation for GNU utilities and libraries is written.

Info files

info, for more information about using Info.

Each node of an Info file may have any number of child nodes that describe subtopics of the node's topic. The names of child nodes are listed in a menu within the parent node; this allows you to use certain Info commands to move to one of the child nodes. Generally, an Info file is organized like a book. If a node is at the logical level of a chapter, its child nodes are at the level of sections; likewise, the child nodes of sections are at the level of subsections.

All the children of any one parent are linked together in a bidirectional chain of `Next' and `Previous' pointers. The `Next' pointer provides a link to the next section, and the `Previous' pointer provides a link to the previous section. This means that all the nodes that are at the level of sections within a chapter are linked together. Normally the order in this chain is the same as the order of the children in the parent's menu. Each child node records the parent node name as its `Up' pointer. The last child has no `Next' pointer, and the first child has the parent both as its `Previous' and as its `Up' pointer.^[2]

The book-like structuring of an Info file into nodes that correspond to chapters, sections, and the like is a matter of convention, not a requirement. The `Up', `Previous', and `Next' pointers of a node can point to any other nodes, and a menu can contain any other nodes. Thus, the node structure can be any directed graph. But it is usually more comprehensible to follow a structure that corresponds to the structure of chapters and sections in a printed book or report.

In addition to menus and to `Next', `Previous', and `Up' pointers, Info provides pointers of another kind, called references, that can be sprinkled throughout the text. This is usually the best way to represent links that do not fit a hierarchical structure.

Usually, you will design a document so that its nodes match the structure of chapters and sections in the printed output. But occasionally there are times when this is not right for the material being discussed. Therefore, Texinfo uses separate commands to specify the node structure for the Info file and the section structure for the printed output.

Generally, you enter an Info file through a node that by convention is named `Top'. This node normally contains just a brief summary of the file's purpose, and a large menu through which the rest of the file is reached. From this node, you can either traverse the file systematically by going from node to node, or you can go to a specific node listed in the main menu, or you can search the index menus and then go directly to the node that has the information you want. Alternatively, with the standalone Info program, you can specify specific menu items on the command line (Top).

If you want to read through an Info file in sequence, as if it were a printed manual, you can hit <SPC> repeatedly, or you get the whole file with the advanced Info command g *. ( Advanced Info commands.)

The `dir' file in the `info' directory serves as the departure point for the whole Info system. From it, you can reach the `Top' nodes of each of the documents in a complete Info system.

Printed Books

A Texinfo file can be formatted and typeset as a printed book or manual. To do this, you need T_EX, a powerful, sophisticated typesetting program written by Donald Knuth.^[3]

A Texinfo-based book is similar to any other typeset, printed work: it can have a title page, copyright page, table of contents, and preface, as well as chapters, numbered or unnumbered sections and subsections, page headers, cross references, footnotes, and indices.

You can use Texinfo to write a book without ever having the intention of converting it into on-line information. You can use Texinfo for writing a printed novel, and even to write a printed memo, although this latter application is not recommended since electronic mail is so much easier.

T_EX is a general purpose typesetting program. Texinfo provides a file called `texinfo.tex' that contains information (definitions or macros) that T<sub>E</sub>X uses when it typesets a Texinfo file. (`texinfo.tex' tells T_EX how to convert the Texinfo @-commands to T_EX commands, which T_EX can then process to create the typeset document.) `texinfo.tex' contains the specifications for printing a document.

Most often, documents are printed on 8.5 inch by 11 inch pages (216mm by 280mm; this is the default size), but you can also print for 7 inch by 9.25 inch pages (178mm by 235mm; the @smallbook size) or on European A4 size paper (@afourpaper). (See Printing ``Small'' Books. Also, see Printing on A4 Paper.)

By changing the parameters in `texinfo.tex', you can change the size of the printed document. In addition, you can change the style in which the printed document is formatted; for example, you can change the sizes and fonts used, the amount of indentation for each paragraph, the degree to which words are hyphenated, and the like. By changing the specifications, you can make a book look dignified, old and serious, or light-hearted, young and cheery.

T_EX is freely distributable. It is written in a superset of Pascal called WEB and can be compiled either in Pascal or (by using a conversion program that comes with the T_EX distribution) in C. (See emacs:TeX Mode,T_EX Mode, for information about T_EX.)

T_EX is very powerful and has a great many features. Because a Texinfo file must be able to present information both on a character-only terminal in Info form and in a typeset book, the formatting commands that Texinfo supports are necessarily limited.

See How to Obtain T_EX.

@-commands

Depending on what they do or what arguments^[4] they take, you need to write @-commands on lines of their own or as part of sentences:

• Write a command such as @noindent at the beginning of a line as the only text on the line. (@noindent prevents the beginning of the next line from being indented as the beginning of a paragraph.)

• Write a command such as @chapter at the beginning of a line followed by the command's arguments, in this case the chapter title, on the rest of the line. (@chapter creates chapter titles.)

• Write a command such as @dots{} wherever you wish but usually within a sentence. (@dots{} creates dots ...)

• Write a command such as @code{sample-code} wherever you wish (but usually within a sentence) with its argument, sample-code in this example, between the braces. (@code marks text as being code.)

• Write a command such as @example at the beginning of a line of its own; write the body-text on following lines; and write the matching @end command, @end example in this case, at the beginning of a line of its own after the body-text. (@example ... @end example indents and typesets body-text as an example.)

As you gain experience with Texinfo, you will rapidly learn how to write the different commands: the different ways to write commands make it easier to write and read Texinfo files than if all commands followed exactly the same syntax. (For details about @-command syntax, see @-Command Syntax.)

General Syntactic Conventions

If you mark off a region of the Texinfo file with the @iftex and @end iftex commands, that region will appear only in the printed copy; in that region, you can use certain commands borrowed from plain T_EX that you cannot use in Info. Likewise, if you mark off a region with the @ifinfo and @end ifinfo commands, that region will appear only in the Info file; in that region, you can use Info commands that you cannot use in T_EX. Similarly for @ifhtml ... @end ifhtml, @ifnothtml ... @end ifnothtml, @ifnotinfo ... @end ifnotinfo, @ifnottex ... @end ifnottex, See Conditionals.

Caution: Do not use tabs in a Texinfo file! T_EX uses variable-width fonts, which means that it cannot predefine a tab to work in all circumstances. Consequently, T_EX treats tabs like single spaces, and that is not what they look like. Furthermore, makeinfo does nothing special with tabs, and thus a tab character in your input file may appear differently in the output.To avoid this problem, Texinfo mode causes GNU Emacs to insert multiple spaces when you press the <TAB> key.Also, you can run untabify in Emacs to convert tabs in a region to multiple spaces.Don't use tabs.

Comments

You can write long stretches of text that will not appear in either the Info file or the printed manual by using the @ignore and @end ignore commands. Write each of these commands on a line of its own, starting each command at the beginning of the line. Text between these two commands does not appear in the processed output. You can use @ignore and @end ignore for writing comments. Often, @ignore and @end ignore is used to enclose a part of the copying permissions that applies to the Texinfo source file of a document, but not to the Info or printed version of the document.

What a Texinfo File Must Have

\input texinfo
@setfilename info-file-name
@settitle name-of-manual

@bye

\input texinfo   @c -*-texinfo-*-
@c %**start of header
@setfilename info-file-name
@settitle name-of-manual
@c %**end of header

The @c lines which surround the `@setfilename' and `@settitle' lines are optional, but you need them in order to run T_EX or Info on just part of the file. (See Start of Header, for more information.)

Furthermore, you will usually provide a Texinfo file with a title page, indices, and the like. But the minimum, which can be useful for short documents, is just the three lines at the beginning and the one line at the end.

Six Parts of a Texinfo File

A Short Sample Texinfo File

Here is a complete but very short Texinfo file, in six parts. The first three parts of the file, from `\input texinfo' through to `@end titlepage', look more intimidating than they are. Most of the material is standard boilerplate; when you write a manual, simply insert the names for your own manual in this segment. (See Beginning a File.)In the following, the sample text is indented; comments on it are not. The complete file, without any comments, is shown in Sample Texinfo File.

Part 1: Header

\input texinfo   @c -*-texinfo-*-
@c %**start of header
@setfilename sample.info
@settitle Sample Document
@c %**end of header

@setchapternewpage odd

Part 2: Summary Description and Copyright

@ifinfo
This is a short example of a complete Texinfo file.

Copyright @copyright{} 1990 Free Software Foundation, Inc.
@end ifinfo

Part 3: Titlepage and Copyright

@titlepage
@sp 10
@comment The title is printed in a large font.
@center @titlefont{Sample Title}



@c The following two commands start the copyright page.
@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1990 Free Software Foundation, Inc.
@end titlepage

Part 4: `Top' Node and Master Menu

@node    Top,       First Chapter, ,         (dir)
@comment node-name, next,          previous, up

@menu
* First Chapter::    The first chapter is the
                     only chapter in this sample.
* Concept Index::    This index has two entries.
@end menu

Part 5: The Body of the Document

@node    First Chapter, Concept Index, Top,      Top
@comment node-name,     next,          previous, up
@chapter First Chapter
@cindex Sample index entry



This is the contents of the first chapter.
@cindex Another sample index entry



Here is a numbered list.

@enumerate
@item
This is the first item.

@item
This is the second item.
@end enumerate



The @code{makeinfo} and @code{texinfo-format-buffer}
commands transform a Texinfo file such as this into
an Info file; and @TeX{} typesets it for a printed
manual.

Part 6: The End of the Document

@node    Concept Index,    ,  First Chapter, Top
@comment node-name,    next,  previous,      up
@unnumbered Concept Index



@printindex cp

@contents
@bye

The Results

Acknowledgements

Our thanks go out to all who helped improve this work, particularly to François Pinard and David D. Zuhn, who tirelessly recorded and reported mistakes and obscurities; our special thanks go to Melissa Weisshaus for her frequent and often tedious reviews of nearly similar editions. Our mistakes are our own.

Internet address:
    bug-texinfo@prep.ai.mit.edu

4. The word argument comes from the way it is used in mathematics and does not refer to a disputation between two people; it refers to the information presented to the command. According to the Oxford English Dictionary, the word derives from the Latin for to make clear, prove; thus it came to mean `the evidence offered as proof', which is to say, `the information offered', which led to its mathematical meaning. In its other thread of derivation, the word came to mean `to assert in a manner against which others may make counter assertions', which led to the meaning of `argument' as a disputation.